Re: [PATCH 3/4] crypto: iaa - use RCU per-package WQ tables

[Vinicius Costa Gomes <vinicius.gomes@intel.com>]

Hi,

Herbert Xu <herbert@gondor.apana.org.au> writes:

> On Mon, Oct 19, 2026 at 04:06:22PM -0700, Vinicius Costa Gomes wrote:
>> rebalance_wq_table() gives CPU n all the WQs of IAA device
>> n / cpus_per_iaa. The flat index ignores package boundaries, so a CPU
>> can be paired with a device on another package, and each CPU sends all
>> its requests to one device while the other devices of its package stay
>> idle. The table is also rebuilt in place, so a request issued during a
>> probe or remove can read a NULL WQ and fail with -ENODEV.
>> 
>> Replace it with one table per package, holding the WQs of every IAA
>> device on that package, and have each CPU round-robin over its package's
>> table. Rebalance builds the whole set of tables and publishes it with
>> rcu_replace_pointer(). The submit paths look the WQ up, and take their
>> reference on it, inside an RCU read-side section.
>> 
>> - A package without IAA devices gets a copy of another package's table,
>>   so the lookup needs no fallback.
>> - Every table has room for all the WQs, a few pointers more than it
>>   needs, so they can be sized without counting per package.
>> - If a rebalance fails, the current tables are kept. On removal they
>>   are cleared instead, because they still hold the removed WQ. Removal
>>   then waits for a grace period before returning, because the idxd_wq
>>   can be freed after that.
>> 
>> Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
>> ---
>>  drivers/crypto/intel/iaa/iaa_crypto.h      |   7 -
>>  drivers/crypto/intel/iaa/iaa_crypto_main.c | 346 ++++++++++-------------------
>>  2 files changed, 117 insertions(+), 236 deletions(-)
>
> Please respond to this comment:
>
> https://sashiko.dev/#/patchset/20261019-iaa-crypto-wq-tables-v1-0-fab67b2a1538%40intel.com
>

Weird that I haven't received any notification about these comments.

Anyway, as I moved some code around, sashiko considers it a "new" issue,
but from a quick look, it's a pre-existing one. Doesn't seem too hard to
fix, will include the fix on v2.


Cheers,
-- 
Vinicius